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~~ ~ ~ ~. RESEARCH NOTES BRITISH COLUMBIfl FOREST 5ERVlCE Q (-5"" F\# "I 6 \a> ______ NO. 41 VICTORIA, B.C., CANADA I966 PLANTING TRIALS WITH PONDEROSA PINE SN BRITISH COLUMBIA BY K. ILLINGWORTH and M.B. CLARK Research Division FOREST SERVICE DEPARTMENT OF LANDS, FORESTS, AND WATER RESOURCES EL C. Forest Service Research Notes are issued at irreylar intervals and distributed on the basls of their lndivioual interest. Therefore, it my not be possible for persons or organrsatians to maintain complete files inasmuch as certain numbers may pertain only to Forest Service problems and hencc be lssued only to Service personnel.

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~~ ~ ~ ~.

RESEARCH NOTES

BRITISH COLUMBIfl FOREST 5ERVlCE Q (-5""

F\# "I

6 \a> ______

NO. 41 VICTORIA, B.C., CANADA I966

PLANTING TRIALS WITH

PONDEROSA PINE SN

BRITISH COLUMBIA

BY

K. ILLINGWORTH and M.B. CLARK

Research Division

FOREST SERVICE DEPARTMENT OF LANDS, FORESTS, AND WATER RESOURCES

EL C. Forest Service Research Notes are issued a t i r r e y l a r intervals and dis tr ibuted on the b a s l s of t h e i r lndivioual i n t e r e s t . Therefore, it my not be possible for persons o r organrsatians to maintain complete f i l e s inasmuch as c e r t a i n numbers may per ta in only t o Forest Service problems and hencc be lssued only t o Service personnel.

PLANTING TRIALS WITH PONDEROSA PINE

I N

BRITISH COLUMBIA

13 Y

K. Illingworth and M. B. Clark

.

ABS TR AC T

V

Trials were established during 1959-62 to test methods of improving the survival of ponderosa pine. Techniques included the mechanical eradication of vegetative competition, shading, planting methods, nursery influences, planting- stock age-classes and morpho- logical grades. The main conclusions are :-

1.

2.

3.

Lack of soil moisture is the factor most limiting for plantation establishment on denuded pine sites.

Site preparation methods reducing vegetative competition for mois ture can improve surv iva l d ramat ica l ly , a re economically justifiable and should be regarded as an essent ia l par t of reforestation practice in this forest type.

Many influences] including nursery regime and seasonal effects, produce variability in planting stocks and weaken traditional expressions of survival potential] such as age and morphological grades. However, in the absence of m o r e acceptable cr i ter ia , large 2 t 1 transplants appear to be best suited for survival and growth on dry ponderosa pine sites.

.

V

TABLE O F CONTENTS

w ABSTRACT

TITLE PAGE

LIBRARY MINISTRY OF FORESTS PARCUMENT BUJLDINGS

VICTOR&, B.C. V8W 3E7

Page No. -

INTRODUCTION l__.l..._._.l.__...................-.-.--..I -. --- 1

THE TRIALS ................................................................................. __.-_ -- --- 3

MODERATION O F ENVIRONMENTAL EXTREMES .".l.l.-..-..l""-II 5

Pr ellminary Attempts .............................................................. 5 . .

Shading Techniques ................................................................ ... - ~ ,l,ll,lll__,.ll______l."l.-l-".-~~~ 6

A Comparison of the Effects of Shading and Si te Preparat ion .............................................................. ".-.. ....__.__._I_-.-....". 7

Site Preparation Techniques . . 9

Season of Site Preparation ........................ 1 2

The Effects of Site Preparation on Early Growth ..... 13

..

Site Preparation in T e r m s of Cost per Surviving Tree _.I_._"__..I_ 14

Age-class and Grade ~ ______ 17

Morphological Characterlst lcs -.- __________ 21 . .

..

RESIDUAL NURSERY EFFECTS AND ROOT PRUNING"..".---.-" 23

Root Trimming .... .. 26

Page m.

PLANTING TECHNIQUE . ""_ .""-

ANIMAL DAMAGE "

DISCUSSION -.I----_ __ """1"

S i t e P r e p a r a t i o n __- - __I-

Plan t ing Stock +." "- -

ACKNOWLEDGEMENTS __

A P P E N D I X

I C l i m a t i c Data - 1959-62

PHOTOGRAPHS

26

27

29

29

31

32

3 3

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1

PLANTING TRIALS WITH PONDEROSA PINE+ V

IN BRITISH COLUMBIA

INTRODUCTION

Although much of the logged-over ponderosa pine forest in British Columbia has been lost to agriculture, urbanization and other u s e s , a rough estimate places the area of unsatisfactorily restocked but plantable ponderosa pine sites at some 60 ,000 ac re s . Of the 20,000 acres of this total which are of better than average site productivity,+ 18,000 occur in the East Kootenay or Rocky Mountain Trench between latitudes 49* 00' and 50° 15' N, (19).

During the period from 1950 to 1960, approximately 3,820 acres were planted to this species. The weighted average survival of 23. 2 per cent is an indication that, with a few exceptions, the history of these plantations had been one of repeated failure. In spite of careful handling and planting of the stock, it was apparent that successful establishment could only be expected in years when relatively cool, moist weather pre- vailed during the growing season, and, therefore, that some means of improving the plant-soil-moisture relationship during years of less c lement weather must be sought. V

Among possible techniques, some of which were eliminated by preliminary tr ials, shading and the control of ground vegetation by s c r e e f h g o r ploughing have long been recognized a s an effective means of improving plantation survival on droughty sites (2) . In addition .. the l i terature suggests that survival is influenced by the morphological and physiological condition of the planting stock; thus, not only the grading practices, but also the nursery treatment could logically be expected to reflect in the field survival of the plantation ( 4 , 8, 14, 17, 18) .

These broad considerations provided the basis for a series of t r ia ls , implemented in the years 1959- 62 inclusive, for the general pur- pose of testing certain techniques which might improve the survival of ponderosa pine plantations in British Columbia.

8 ::: Experimental Projects 550, 551 , 552, 560, 57 2 and 597

t Average height of dominant t rees , 65 f ee t a t 100 years .

- 2 -

GENERAL DESCRIPTION O F THE AREA w

The trials are contained in the ' parkland zone' of the Ponderosa Pine and Douglas Fir Section of the Montane Forest Region (5) . This zone has a distinctive climate, which is notable for i ts comparatively low precipitation and high summer temperatures. Mean annual precipitation varies between 10 and 20 inches, much of this fall ing as snow. Long periods of sunshine during the summer, together with an inflow of hot , continental air from the south, result in high daily temperatures-- July maxima greater than 95O Fahrenheit are not uncommon. Desiccating southerly winds, frequently reaching speeds of 20 m. p. h. , prevail in the Rocky Mountain Trench, and, in much of the region as a whole, semi-arid conditions are approached. These are only sl ightly moderated by the localized influence of large bodies of water, such as occur in the Okanagan Valley. A tabular summary of da ta , recorded a t representa t ive s ta t ions during 1959-62 inclusive, i s presented in Appendix I.

The soils with which ponderosa pine is associated are predominantly Brown Wooded, and the till and fluvio-glacial materials from which they are der ived is often strongly calcareous, especially in the East Kootenay. Throughout a profile, the reaction may vary from pH 6. 1 to 9. 0. The textures are mainly loam and s i l t loam, occasional ly with a mantle of loess , but quantities of gravel, stones and boulders in the profile vary from sl ight to excessive. In the East Kootenay, the most extensive and, from the forestry point-of-view, important series within this soil group a r e the Elk0 Silt Loam and the Wycliffe Silt Loam ( 6 , 7). Respectively, these occur upon the relatively flat outwash and ' gravelly glacial r iver deposits ' , and upon the morainic and drumlinized uplands between 2,600 and 3,700 feet above sea level. Excessive drainage and the highly cal- careous parent material combine with the hot, dry summers to make availability of soil-moisture the most important l imiting factor for tree growth throughout much of the region.

The principal forest cover comprises many-aged, open stands of ponderosa pine and Douglas-fir, most commonly in association with blue- bunch wheatgrass (Agropyron spicatum var. inerme) and fescue (Festuca scabrella and F. idahoensis). A dense shrub layer, dominated by antelope bush (Purshia tr identata) is sometimes present. This species is most prolific on logged-off lands in the southern part of the Rocky Mountain Trench, where i t consti tutes a hindrance to reforestation.

"- -

Exploitation of the virgin ponderosa pine forest was largely com- pleted 30 to 50 years ago, concomitantly with the growth of a ranching economy. Repeated ground fires, overgrazing by livestock and game, and

W - 5 -

lac’lbf sufficient seed have, until recently, kept forest regeneration to a minimum and resulted in extensive areas of denuded and degraded land with only a marginal agricultural potential. It i s with the rehabilitation of these si tes that this study is concerned.

THE TRIALS

The t r ia ls are in two s e r i e s , one in the Okanagan Valley (1959-61) , and one in the East Kootenay (1960- 62). The former is located on previously-cultivated benchland adjacent to Lambly Creek on the west bank of Okanagan Lake, while the several blocks of the la t ter are dispersed throughout the ponderosa pine zone of the Rocky Mountain Trench, between Canal Flats and the Montana border. Al l the tr ials were established on what are considered to be severe si tes. The two s e r i e s were commenced independently, but the similarity of preliminary results subsequently led to a co-ordinated approach.

Although the t r ia ls w e r e modified each year, they retained sufficient in common to provide some seasonal replication of the factors of pr imary interest. Attention was focussed upon what were considered to be the mos t effective and economical methods of obtaining better survival. A three- block, randomized block design was common to all the tr ials , and plots were spli t according to the number of factors to be studied. Analyses were based upon the results of complete enumerat ions carr ied out in the fa l l of each year , t reatments being tes ted and compared in terms of survival and, where possible, cost of establishment.

U

Finally, the interpretation of differences between various types of planting stock were facilitated by morphological measures of replicated 15-tree samples; these were randomly drawn at the t ime of lifting.

Table 1 summarizes the t r ia ls a s they were established on the ground. For the purpose of this report , however, the methods w i l l be described, and results presented and discussed under convenient headings.

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Table 1. TAEULAR SUMMARY OF THE TRIALS V

(I)

Experimental Project

No. Spring

Planted Location

(Replications)

4

Factors for which Comparisons were Planned

5 50

551

552

5 60

57 2

597

1959

1960

1960

196 1

1961

1962

Lambly Ck. ( 3 )

Lambly Ck. ( 3 )

Findlay Ck. ( 1 ) TaTa Ck. (1) Newgate ( 1 )

Lambly Ck. ( 3 )

Findlay Ck. ( 2 ) TaTa Ck. (1)

Findlay Ck. (1) McGinty Lake (1)

Wardner (1)

Planting techniques Watering Shading Fe r t i l i ze r

Furrowing Manual and mechanized

screefing Shading

Nursery soil amendments Root trimming Furrowing Manual sc r eef ing Shading

Planting techniques F r e s h vs. weathered furrows Planting stock classes Nursery effects

Mechanized screefing F r e s h vs. weathered furrows Planting stock classes Planting stock grades

Furrowing technique Manual and mechanized

screefing Planting stock classes Planting stock grades

W

I I i

w

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MODERATION O F ENVIRONMENTAL EXTREMES

Preliminary Attempts

The f i rs t formal a t tempts to improve plantation survival by manipulating environmental factors were made in 1959, when the effects of mulching, watering and fertilizing upon the survival of 2 t 0 seedlings were demonstrated at Lambly Creek. In combination with various planting methods, with which there were subsequently shown

detectable interactions, the treatments comprised:-

Paper mulch, A one-square-foot collar of building paper was placed flat on the ground around each plant, and weighted down with two or three stones. I ts purpose was to conserve moisture in the seedling' s root zone by reducing evaporation.

Watering;. Plants were watered at the rate of one gallon per plant per application. There were three treatment levels (see Table 2).

Control. None of these treatments was applied.

Fer t i l izer , For addi t ional interest , half of the trees in each of the above treatments were planted with a Mora ' Tree Feed Standard' pellet (a urea-formaldehyde preparation comprising 28 per cent nitrogen and 5 per cent phosphate) in each planting hole.

Although the survival after one growing season was still poor, the beneficial effect of the paper mulch was very pronounced. Watering was, on the average, significantly better than no t reatment , but the value of one watering at the end of the first month was doubtful. This is not surprising; spring run-off and precipitation are at a peak in May and June, and the plants would benefit little from additional moisture at that time.

The fert i l izer pellets produced a highly significant negative response--an effect characterist ic of ni t rogenous fer t i l izers on water deficient soils. The average survival of non-fertilized seedlings was 28. 8 per cent, compared with 15. 1 per cent for fertilized seedlings.

- 6 -

Table 2. E F F E C T O F A MULCH AND WATERING TREATMENTS W O N FIRST-SEASON SURVIVAL O F 2 t 0 SEEDLINGS

-

Mean Survival Per Cent 1 Treatment

-

Mean Survival Per Cent 1 Treatment

Paper mulch

Watering at end of f irst , second and third months

Watering at end of first and second months

Watering at end of first month only

32 . 1

22.0 1

21. 7 ) 20.8 ) ) 18. 9

Control 1 15.0

.

Basis : 1 , 200 t rees per t reatment . No significant difference between bracketed means.

V

The results of these prel iminary t r ia ls served to emphasize the importance of moi s tu re a s a l imit ing factor , and, therefore , fur ther attempts to develop a more effective and practical way of improving plant- soil moisture relations were continuedin 1960. These included shading treatments and methods of eliminating or reducing vegetative competition for moisture ((henceforth referred to a s si te preparat ion) .

Shading Techniques

Five shading treatments were tested in combination with four si te preparation treatments at Lambly Creek, Large 2 t 0 seedlings were planted in holes prepared with a power-driven auger and 6-inch diameter bit. The shading treatments were:

i a )

(b)

Recessed planting. The seedling was planted in the auger hole so that the planting surface (root collar - ground line) was roughly 2 inches below the surrounding ground level.

Veneer band. A stapled veneer band, approximately 4 inches high and 6 inches square , was placed around each tree.

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i

*c) Aluminum foil, - The seedlings stem was wrapped with aluminum foil, shiny side out to reflect the heat.

(d) Shingle. A shingle was placed on the south west side of each t r ee to provide lateral shade during the hottest part of the day.

(e) Control. No treatment. -

The results after one season are presented in Table 3 . Regardless of the method of si te preparation (p. 9 ) , there were no detectable differences in survival between shading treatments and the control. Mortali ty during the next three years d!.d not alter this situation. Thus, i t is apparent that the shading methods tested have no real value when used in combination with auger planting,

Table 3 . COMPARISON O F FOUR SHADING TREATMENTS. FIRST SEASON SURVIVAL O F AUGER- PLANTED 2 t 0 SEEDLINGS.

Shading Treatment Mean Survival Per Cent w

Recessed planting

Shingle

49. 9

46. 9

I Control I 44. 8

V en ee r band

Aluminum foil

44.0

40. 8

Bas i s : 1 , 200 t rees per t reatment .

A Comparison of the Effects of Shading "_ and Site Preparation

In 1960, shading was included in a comparison of si te preparation 1

treatments in the Rocky Mountain Trench. 2 t 0 seedlings were mattock- planted::: in combination with the fol'lowing treatments :

W :I: In British Columbia, the most common planting method is the vertical

sl i t , or notch, using a B. C. Forest Service grub hoe (hereaf ter r e fe r r ed to a s a mattock).

- 8 -

Shading. Trees were notch-planted in unprepared ground, V lateral shade being provided by one o r two cedar shakes on the south-west side of each tree.

Screefing and mattock planting. Small patches, approximately 12 inches square, were screefed (scalped) down to minera l so i l , and a tree was notch-planted in the centre of each patch.

Mattock planting in ploughed furrows. Single furrows were made e i ther by an International TD-9 ( o r its equivalent) with a tilted blade (13j, or by a tractor and plough (Deereborne two- bottom 14-inch). Since the planting sites were relatively flat, the furrows were orientated in an east-west direction: the spoil being turned over on the south side of the furrow,

Control, Trees were notch-planted in unprepared ground.

The summer of 1960 was hotter and drier than usual (Appendix 1,: and the mean survival of all the plantations, totalling 6 000 t r ees , was on1.y 34.4 per cent at the end of the first growing season. However.. as can be seen in Table 4, outstanding differences in survival exist between: and are a t t r ibutable to the treatments. There were no interactions with either nursery soi l amendment or root-pruning t reatments , tes ts of which had been incorporated in this trial (p . 23).

Table 4. COMPARISON OF SITE PREPARATION AND SHADING EFFECTS IN TERMS O F P E R CENT SURVIVAL DURING THE FIRST THREE YEARS

Treatment

Furrows

Screefed only

Shaded only

Control

T 1960

72. 4

28.4 I

25. 2 )

15. 4

Mean 34. 4

Year

1961

64. 6

22.5 ) j

18.8 )

8.6

~-

26.7

- 1962

61.7

-

19. 2 I

16.6 ) I

6.7

23. 8

Percentages based on 1, 500 trees per treatment. Bracketed f igures are not significantly different.

.

.

W

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w The most str iking feature of the tr ial was the consistently h igksurv iva l of t rees planted in furrows, regardless of site or planting stock. Screefing and shading, although better than notch-planting alone, were very much poorer, there being no real difference between the two.

established during the first growing season and did not change thereafter. 'i As in the case of all the tr ials described above, treatment ranking was

This comparison demonstrated the beneficial influence of shading, compared with no t r ea tmen t a t a l l , but it was also apparent that the provision of shade is not vital when vegetative competition is reduced, if only by a 12-inch screef or ; as demonstrated in the Okanagan, a 6-inch diameter auger hole.

Site Preparation Techniques

The mechanical elimination of vegetation entails either furrowing or screefing, variations being a question of degree rather than kind.

In these t r ia ls , screef ing was carr ied out : (a) manually, using a mattock to c lear a relatively small (1 2-inch-square) patch of mineral soil; ib) by machine, using a ' skogskultivator' t --a Swedish scarifying implement which rips out a 36 by 18 by 4-inch patch at intervals of s ix feet. This was drawn by a variety of wheeled and tracked machines, the efficacy and economy of which w e r e largely dictated by the site conditions.

w

Single furrows were prepared with: (a) a tilted bulldozer blade; rbj a tandem plough mounted by a three-point hitchon a rubber- t i red t rac tor ; (c j a ' Deschutes' , double-mouldboard fireline plough, drawn by a Caterpi l lar D-6.

In 1960, a comparison of site preparation techniques in the Okanagan gave the results depicted graphically in Figure 1. The t rees , all two-year-old seedlings, were planted in holes prepared with a 6-inch diameter auger. There were no interactions between site preparation and the shading treatments previously described (pps. 6 and 7) .

All the site preparation treatments markedly improved survival, furrowing being especially beneficial. While effective, there was no difference between the skogskultivator and mattock screefs.

e "

::: Manufactured by AB Skogsbruksmaskiner, Vasagatan 5 2 , Stockholm C , Sweden.

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0 0 0 a 8 0

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x- 4 0 -I

.

.

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- 1 1 - w In 1963 , depredations by Columbia ground squirrel

(Sgrmophilus columbianus columbianus (Ord. ) were observed in Block 3 , being particularly severe among the furrows. This caused a significant change in treatment ranking, which, however , had not

< materially altered in the undisturbed blocks.

During the third and fourth years, a sl ightly heavier mortali ty rate was noted in furrows on shallow soil (Block 1). While this may not be important, it is conceivable that the early restriction of root development by calcium carbonate concentrations may consti tute a hazard peculiar to furrow- or deep-planting on such soils.

In summary, it should be noted that, as in the East Kootenay trial, trees planted without any site preparation failed almost completely.

In 1962, a further comparison was made in the East Kootenay. T rees of four age-classes and two s ize grades were mat tock-planted in combination with the site preparation treatments shown in Table 5.

Table 5. COMPARISON OF FOUR SITE PREPARATION TREATMENTS IN TERMS O F PER C E N T SURVIVAL AFTER TWO GROWING

SEASONS

Method

Furrows

Furrows

Screef

Mattock- sc reef

Machine

Deereborne two-bottom 14" plough

Oliver OC- 3 John Deere 430 and TD-9 with

tilted blade

Skogsku1tivat;or and John Deere 430

""""""-"""""-

Mean Survival Per Cent 1

74.1 1 ) 1 )

71.6 ) 1

1 70. 7 )

51. 9

Per cent based on 1 , 080 trees in each method. Bracketed f igures are not significantly different.

- 12 -

W The need for thorough s i te preparat ion, f i rs t apparent in the U

East Kootenay in 1960 (Table 4 j : w a s again demonstrated; the survival obtained by mattock-slit planting in manually screefed patches being very significantly poorer than that obtained by any other method. The difference? which was of the o rder of 20 per cent , w a s not as pronounced as in 1960: and this i s a t t r ibuted to damper, cooler weather during the 1962 growing season.

It is notable that , regardless of variation between test si tes and size and age of the planting stock: all the mechanized methods of site preparation gave equally good survival--a result which confirmed those obtained during the previous year (Table 6) . However, methods did differ in t e rms of cost per surviving plant (Table 8).

Season of Site PreDaration

In 1960, it had been observed that some of the mortality among stock planted in f u r r o w s w a s caused by the sod o r spoil sloughing o r being kicked by animals back into the furrows, thereby smothering the plants. Hence, in 1961, an attempt w a s made to determine if a weathering period pr ior to planting would provide more stable furrows and minimize this effect. ' Weathered furrows' were ploughed in the autumn prior to spring planting ~ while ' f resh fur rows ' were p repared a t the t ime of planting. First year survival in the Okanagan tr ials showed that there w e r e no real differences between the two, regardless of site, planting method or planting stock. Survival in fresh- and weathered-furrows w a s 73 and 79 per cent respectively.

Table 6 summarizes the survival after three growing seasons in an East Kootenay tr ial of timing and methods of si te preparation. There were no interactions with the planting stock age-classes and size grades which were also being compared.

Except for a negligible difference of 3 . 9 per cent between fall- and spring-bulldozer furrowing.. which disappeared after the first growing season, the benefits expected of weathered furrows did not materialize.

By the end of the th i rd year , a survival difference of 10 per cent was manifest between the spring- and fall-skogskultivator treatments, the latter being the poorest, This is attributed to the difficulty of obtaining a satisfactory screef in dry: sunbaked ground (fall, 1960). Many of these spots were soon recolonized by vegetation, whereas those prepared in moist ground during the spring remained comparatively bare.

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Tal”- “2 6

Me tho d

Furrows

Furrows

Fur rows

Scr eef

w ” 1

+

I

MEAN SURVIVAL AFTER THREE GROWING SEASONS, B Y TIME AND METHOD OF SITE PREPARATION.

Machine T

Deschutes double- mouldboard plough

Deereborne two- bottom 14- inch plough

D-6 or Ol iver OC- 12 with tilted blade

Swedish Skogskultivator and Ford Tractor

Survival Per Cent I

Weathered Site Prep.

90.4

85. 8

76. 3

F r e s h Site Prep.

91. 6

84. 3

84. 0

86. 5

Mean

91 .6

87. 5

84.9

81. 7

Based on 1 ~ 200 trees for each t ime and method of si te preparation.

2 Plough drawn by a rubber - t i red Ford t rac tor .

To summarize, while weathered furrows did not pro Ive to b e directly beneficial in either the East Kootenay or the Okanagan trial, it was shown that, provided the ground is not too hard , ploughing o r furrowing can be carried out at any convenient t ime during the autumn, winter , or immediately pr ior to planting.

The Effects of Site PreDaration on Earlv Growth

The question was raised as to whether si te preparation might have deleterious side effects on tree health and vigour. Though the plantations were too young to be assessed for long term effects , measure-

f a r f rom being inhibiting, the complete removal of vegetative competition resulted in a highly significant increase in height increment, regardless of si te or type of stock. As shown in Table 7 , in absolute terms this incre- ment i s s l igh t , but relatively i t represents an increase of a s m u c h a s 48 per cent.

i ments of height and leader growth four years after planting indicate that,

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Table 7. EFFECT OF SITE PREPARATION ON EARLY GROWTH, EAST KOOTENAY TRIALS, 1962.

Site Preparation

Furrows - Blade

- Elade

Screef- Skogskulti- vator

- Mattock

r I ~ ~~

Tree Height after ?our Growing Seasons

(inches)

9. 3

Leader Growth in Third Growing Season

(inches)

2. 5 ) )

N. B. Bracketed figures not significantly different.

The significant differences in tree heights between manual and mechanical methods of si te preparation might be explained in terms of differences in the depth and thoroughness of cultivation; it appears safe to conclude , therefore , that , in addition to the primary benefit of increased survival , mechanical s i te preparat ion has not yet adversely affected the vigour of the crop, indeed, this may even have been improved.

Si te Preparat ion in Terms of Cost per Surviving Tree -

V

Commencing with the 1960 Okanagan trial, an attempt was made to assess t rea tments in t e rms of total cost per surviving tree. On this bas i s , i t is apparent that site preparation substantially reduces establishment costs, but fa i lure to prepare the si te can be an expensive

omission (Table 8).

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- 16 -

2.

3.

Plant ing costs are averaged for a l l repl icat ions, s i te preparat icy treatments and planting stock classes. Nursery costs are for four age-classes and average $12.02 per M.

Nursery costs for four age-classes average $20.80 per M. and thereby mask the reduced si te preparation costs, All costs are calculated on the basis of 6 feet spacing in lines 12 feet apart. Supervisory costs, which are out of proportion in such tr ials, a r e excluded.

It was evident that the cost of site preparation could be justified in t e rms of improved survival. Even so , costs varied widely with: ia) site and (b) type of machine used. Thus, on sites with much antelope bush or many windfalls and stumps, the plough and skogskultivator were inoperable without prior clearing; nor was the plough suitable for very stony si tes. Conversely, costs rose proportionately with the use of over- powered equipment. For example, at a spacing of 12 feet between planting l ines, skogskultivator costs ranged f r o m $2. 16 per a c r e on uncluttered sites where the implement could be drawn by a fast , wheeled t ractor , to $10. 44 per acre on a windfall-littered site where clearing with a Caterpi l lar D-6 was a prerequis i te . On s i tes such as the las t ment ioned, costs were subsequently halved by the use of a light bulldozer (International TD-9) to draw the skogskultivator and clear the planting lane simultaneously. Similarly, when clearing was not required, especially on deep, stone-free loams, the plough-Ford tractor combination was faster and, therefore, cheaper ($7. 56/ac. ) than other furrowing methods , e. g. an Oliver OC- 12 and tilted blade ($10. 08/ac. ) .

i 1)

' 2)

( 3)

The results may be summarized as:-

the skogskultivator was the cheapest method of si te preparation, and was as effective as furrowing on all but the Okanagan test s i tes ;

the costs of operation of the plough/tractor combination were prohibitive on all but the most workable sites where ploughing could be done rapidly without prior clearing with a dozer ;

furrowing with a tilted dozer-blade was effective and economical, provided that a reasonable match of horsepower!job requirements could be obtained.

w

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W

V

It is apparent that the si te conditions must dictate the selection ofwethod and machine, and that costs can be reduced by the intelligent manipulation of these variables. Where possible, l ight, fast tractors should be used, but when some form of clearing is necessary, th is operation should be combined with site preparation through the use of a light to medium bulldozer.

The important conclusion which must be drawn from all the t r ia l s is that the reduction of vegetative competition is not only essential to plantation establishmenc on dry sites, but is also economically justifiable.

PLANTING STOCK CHARACTERISTICS

Age-class and Grade

Several planting stock classes were compared in terms of their survival in the field. All the stock for the East Kootenay trials was raised at the East Kootenay Nursery from one seedl.ot, and, in 1961, it comprised the following age-classes: 2 t 0 , I. t 1 , 1 t 2, and 2 t 1. These were divided into large and small grades on the basis of top-length and root-collar diameter. All classes and grades were mattock-planted in combination with the furrowing and screefing treatments previously described.

During the three years of observation, the survival of three- year-old transplants was invariably better than that of two-year-old trans- plants and seedlings. In this period also, a slight but most consistent difference between large and small grades increased from a mean of 1.7 to 7.7 per cent. By 1963, the survival of these grades was 88.4 and 80.7 per cent respectively, There were no inter-actions between age-classes, grades, locat ions or s i te-preparat ion t reatments .

Corroboration was provided by a t r ia l of the same planting stock in the Okanagan. The results of the two t r ia l s a re , therefore , p resented together in Table 9. They temptingly suggest some general conclusions about age-classes, but, as w i l l be shown below, there are important reservations.

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Table 9. COMPARISON O F FOUR AGE-CLASSES FROM THE SAME y SEEDLOT AND NURSERY, IN TERMS O F THIRD-SEASON

SURVIVAL AND COST PER SURVIVING PLANT.

Location

Age-class Eas t Kootenay Okanagan Survival ( 7 0 ) 1 Cost (4) 3 Survival ( 7 0 ) L c o s t (# ) 3

2 t 1

10. 6 37.2 5. 7 75.7 ) 1 t 1

9. 3 36. 5 ) 4. 7 77.6 1 2 t 0

7.0 61.3 ) 5. 4 91.5 l t 2

7. 5 65.3 ) 6. 1 91.4 ) 4 1

) )

1. Bas i s : 1 ,000 t r ees per age-class; 2. Bas i s : 600 t rees per age-c lass ; 3. Cost includes site preparation, planting and nursery costs ( 1 t 2 - $13. 57; 2 t 1 - $19.81; 1 t 1 - $10.09; 2 t 0 - $4. 59 per M. excluding lifting costs); 4. Bracketed f igures do not differ significantly, but differences between bracketed pairs are highly significant.

Incorporated in the Okanagan trial was a comparison of 2 t 0 and 1 t 1 stock from a different seedlot and nursery ( see Figure 2). Differences in survival developed between these classes during the third year , and upset the apparent conformity of the data in Table 9.

As shown in Figure 2, of the two age-c lasses ra i sed a t Green Timbers Nursery , 2 t 0 stock gave higher third year survival than 1 t 1 , and considerably higher survival than 2 t 0 seedlings from Kelowna Nursery. Indeed, it compared favourably with the best of the East Kootenay stock.

The data indicate that differences between classes may be subject to effects from the nursery of origin and possible provenance (seedlot). Statements regarding planting stock age-classes should, therefore , be qualified by reference to these factors.

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- 20 - U

In 1962, the East Kootenay trial was repeated, using the same w seedlot as before , but with 3 + 0 seedling instead of 1 t 1 transplants. The resul ts are summarized in Table 10.

Table 10. MEAN SURVIVAL IN PER CENT1, AND COST PER SURVIVING PLANT AFTER TWO GROWING SEASONS, BY AGE-CLASSES

AND LOCATIONS.

I Locations Class Findlay Creek McGint

Y O # Y O

2 + 1 83.0 6.9 68.6

2 T 0 80.3 5. 2 61. 4

1 + 2 78. 1 9. 2 5 2 . 4

3 t 0 60.7 8 .6 61. 8

-7" Lake

7. 8

6. 2

10.3

7.7

T Mean

Wardner Survival l A v e r a g e per Survivor YO

90.0

66.6

62. 4

32. 7

6. 6 69.9 )

10.2 64. 8 ) 1 3

6.0

9.9

15. 11 51. 8 I 10.4

Differences between classes varied from location to location, to some extent reflecting the recorded pattern of animal damage sustained during the first year. At one location in particular, viz. McGinty Lake, heavy mortality caused by cattle trampling reduced second-year differences between classes. But some confirmation of the ear l ier resul ts was obtained: (a) the difference in survival between large grades (72. 7 per cent after two years) and small grades ( 6 1 . 7 per centj was most consis tent , regardless of age-c lass , s i te o r method of si te preparation;. rb) the survival of 2 t 1 transplants was distinctly better than that of a l l other classes, while that of 3 t 0 seedlings was the poorest. Significantly, there was no difference between the survival of 1 + 2 and 2 + 0 stock; this is tentatively attributed to the poorly balanced type of plant comprising the 1 + 2 class in 1962. Like the 3 t 0 stock, i t was character ized by heavy tops (approximately 18 cms. j and low root-top ratios (oven-dry weights).

Thus, in addition to the variability introduced by possible nursery and seedlot effects , the variation in planting stock quality from one year to the next makes broad generalizations on the relationship between age- class and survival extremely questionable. ' I y

- 21 -

u By the same token, comparisons of planting stock in terms of cos&er surviving plant (Tables 9 and 10) a re no t too informative, although they do show that improved survival may well justify the extra expense of producing quality stock.

Morphologic.al Characteristics -

In the East Kootenay trials , the apparent superiority of 2 t 1 transplants , and of large grades compared to small , was consistently indicated. That this cannot be explained solely in terms of the size charac te r i s t ics of the stock is shown in Figure 3. The implications a r e :

(a) Size, possibly as a reflecti.on of inherent vigour, would appear to be important within a given age-class, a conclusion which provides some justification for within-class grading on the basis of s ize character is t ics .

-

(b) But between age-classes, i . e. f rom one age-class to the next, the relationship between survival potential and size is obscure. In these tr ials, survival was not consistently correlated with any individual characteristic , such as root-col lar d iameter , except in extreme cases where, for example, the association of grossly heavy tops with weak root systems suggested a relationship between low survival and a low root/top ratio. Thus, i t seems clear that the quality of planting stock cannot be adequately or reliably expressed in terms of one o r a simple combination of the several in ter-related s ize character is t ics .

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(3

U V

- 23 - w RESIDUAL, NURSERY EFFECTS AND ROOT PRUNING

w An attempt was made to determine whether, through improved

size and vigour of the stock, nursery soil amendment treatments have an effect upon subsequent field performance. The plants were 2 t 0 ponderosa pine from one seedlot. They were raised at the East Kootenay nursery in experimental beds which had received 3-inch top dressings of either stable manure, tankage (sewage), local acid topsoil, spruce needle l i t ter , horticultural peat, or sawdust. Other beds were innoculated with mycorrhiza, while the control beds received none of these treatments.

Two trials were conducted. One was limited to a tes t of three soil amendment treatments in combination with four shading or site prepara- tion methods (c.f. page 7). The selected t reatments were: l i t ter , tankage and peat, representing small , medium and large material respectively. This abbreviated test supplemented a complete t r ia l of the eight soil amendment stocks planted in furrows only.

To facilitate handling and planting the stock, it is a common practice to trim the roots at the planting site. To test for any side effects of this treatment, half of each of the soil amendment lots had their roots pruned to eight inches below the root collar, and the remainder had their

e roots pruned to twelve inches.

Residual Nurserv Effects

In the l imited tr ial , the survival of plants from the tankage- amended bed remained, after three years, dist inctly higher than that of the other two t rea tments , regard less of si te preparation or shading.

The effect of root-trimming was slight and varied with soil amendment treatment,

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Table 11. MEAN SURVIVAL IN P E R CENT ’, AFTER THREE GROWIF’” SEASONS, O F THE LIMITED SERIES O F SOIL AMENDMEN I /

U” ROOT-PRUNING TREATMENTS IN COMBINATION WITH FOUR

PLANTING METHODS.

Nursery Soil Amendments Roots

Tankage Li t ter Pea t Me an

8 inches

22. 3 17. 0 19. 7 31. 1 Mean

23. 6 19. 5 22. 8 29.0 12 inches

21. 1 14. 6 16. 9 33. 4

1 Basis : 1,000 t r ee s in each amendment/root-pruning treatment.

The above results corroborated those obtained from the complete t r i a l of amendments in furrows :-

Table 12. MEAN SURVIVAL IN P E R CENT1, AFTER THREE GROWING SEASONS, OF THE COMPLETE SERIES OF SOIL AMENDMENT/ ROOT-PRUNING TREATMENTS PLANTED IN FURROWS ONLY.

Roots

8 inches

1 2 inches

W

W

awdust I Pea t

:::: 1:::: 47. 6 51. 2

r Lit ter

.”

50. 1

61.9

56.0

rrsery Soil Amendments Control I Tankage I MycorrhizalManurefopsoil - .~_. . .. ..

” - I M e a n

61. 7

64. 8 78. 1 74. 6 71. 2 71. 0 65. 5

65.9 77. 6 80.3 68. 7 69. 2 69. 2

63. 8 78.7 68. 3 73. 7 72. 8

Any two means not underscored by the same l ine are significantly different.

Basis : 125 t r ee s in each amendment/root - pruning treatment.

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w

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- 25 -

TOPSOIL

TANKAGE

60 LITTER

LfBRARY MINISTRY OF FORESTS PARttAMENf BUILDINGS

VlcXJRk, B.C, v8w 3E7

a W

30 o 1 2 4 6 8 10

LENGTH OF TOP (cms) TOPSOIL

W 2 60 L L l T T E R

40 1 SAWDUST v)

30 I . I I 0 I 2 3 4 5

ROOT COLLAR DIA. (mms) =TOPSOIL

I- z 'O W

= TANKAGE

0 oc - W 60 - LITTER

a -PEAT

J

3 5 0 -

(I: 3 40 -SAWDUST v)

5

I

30 0 I . 1

IO0 200 300 400 500 600

ROOT/TOP RATIO (oven dry ut.)

FIGURE 4: THIRD YEAR SURVIVAL OF PLANTS FROM A SELECTION

OF NURSERY SOIL AMENDMENT TREATMENTS, ROOT-

PRUNED TO 12 INCHES AND PLANTED IN FURROWS.

SURVIVAL WAS RELATED TO NURSERY TREATMENT

BUT NOT, APPARENTLY, TO SIZE.

At the end of the f irst growing season, September, 1960, the sawdust, peat and litter treatments were observed to have resulted- in distinctly lower field survival than either the control (no amendment) or other t reatments , but af ter two growing seasons none of the t reatments differed significantly from the control. The ranking of amendments accord- ing to survival remained basically unchanged during the three years of observation. These results indicate that f ield survival may have been strongly influenced by the type of nursery soil amendment. Since there is no obvious relationship between survival and size of the stock (Figure 4), i t would appear that the effect of seedbed amendments upon survival is independent of their effect upon plant size.

Root- Trimming

Trimming the roots to 8 and 12 inches (below the root collar) at the planting site had no detectable influence upon survival during the first two growing seasons, neither as a main effect nor in interaction with amendment and planting treatments. But analyses indicate that, by the end of the third season, root-trimming, considered either alone or in inter- action with amendment treatments, had a smal l but highly significant effect upon survival (Tables 11 and 12). It is suggested that the practice be res t r ic ted to plants having, in addition to undesirably long primary roots, a well-developed system of secondary roots.

PLANTING TECHNIQUE

Early tr ials had sought to obtain better survival through improved planting techniques, and , in 1957, observations in two experimental plantations in the East Kootenay suggested that notch-planting with the B. C. Forest Service grub hoe ( I mattock' ) gave better survival than did planting in holes drilled with a 4-inch diameter, power-driven auger (1 6).

But evidence provided in 1959 by an Okanagan comparison of four planting techniques did not support the East Kootenay observation. The survival after one growing season is summarized below, and no change in this ranking was recorded during the ensuing two years ' observat ion.

Planting Technique Mean Survival (7')

Shovel hole - roots spread 29. 7

Auger hole (6-inch diameter)

Mattock hole - roots spread 22 .9 22. 1 i Mattock slit 13. 1

Percentages based on 1, 500 trees per treatment. No real difference between bracketed figures. )

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- 27 -

w The comparison was repeated in 1961, in conjunction with tests of mnting stock classes and si te preparation methods. Differences established by the end of the f i r s t growing season changed but little during the next three years. Per cent survival after one season was:-

Planting Technique Unprepared Weathered Furrow Fresh Furrow'

83. gT 76 .9 Auger

62.0 (Screefedj 68. 7 80.4 Mattock

47. 1

2

- Percentages based on ( 1 ) 1 ,050 t r ees , ( 2 ) 900 t rees in each site preparation/planting treatment.

While both techniques gave equally good survival on fresh furrows, the auger was better in weathered furrows. The superiority of 'mat tock- screefs ' to the auger on unprepared ground supports East Kootenay experience and is attributed to the more thorough reduction of vegetative corn petition.

ANIMAL DAMAGE w

In the East Kootenay? none of the experimental blocks was protected from animals. Planting si tes in this region are subject to heavy use by both domesticated and wild ungulates (principally elk, Cervus canadensis nelsoni Bailey, and white-tailed deer Odocoileus virginianus ochrourus Bai ley) , as wel l as by a high rodent population. On an operat ional scale , fencing is considered to be uneconomical, and chemical repellents have not been used. An interesting facet of these t r ia ls , therefore , was the possible effects of planting method and planting-stock class and grade upon the susceptibility of plants to browsing.

.

Animal damage takes the form of several degrees of browsing intensity, trampling and complete smothering by turf, soil and faeces. While these investigations did not originally purport to examine these effects, some data on browsing damage during the first year were collected and a re summar ized below. It was subsequently observed that plants, even when severely cut back, are generally able to recover, provided that the damage is not repeated. But it is tentatively suggested that , in the drier climatic zones, the ability to recuperate from repeti t ious browsing may be limited by the aridity of the soil.

- 28 -

In 1961, after one season, a highly significant difference in the percentage of plants browsed was noted between classes and grades of w stock, the smaller classes and grade tending to be more heavily browsed.

Table 13. PERCENTAGE O F PLANTS BROWSED DURING THE FIRST SEASON, BY AGE-CLASS AND GRADE

Age-Class

2 t 0 2 + 1 I t 2 1 t 1

" - Grade

Large

Sma 11

1. 4 1.9 27.5 3. 5

5. 1 13. 1 45.0 8.0

Percentages based on 500 t rees in each age-c lass /grade .

These observat ions were corroborated by the f i r s t s eason r e su l t s of the 1962 tr ials. Small grades were 11. 5 per cent browsed, compared with 5. 9 per cent in the la rge g rades - a small but very consistent difference.

Table 14. PERCENTAGE OF PLANTS EROWSED DURING THE FIRST SEASON, 1962 TRIALS

1 Elock Class

1. 8 16. 4 17. 1 2 + 0

29. 2 9. 8 7.9 3 -?. 0

3. 5 16. 2 7 . 4 1 -t 2

0. 2 8. 6 3 . 1 2 -i 1

Findlay Creek Mc Gin ty Lake Wardner

Percentages based on 360 t r e e s of each age-class per location.

W It was also noted that stock planted in angle-dozed furrows was not- heavily browsed as that in hand-screefed patches.

Site Preparation Method - Plants Browsed (per cen t )

Bulldozer blade

Plough

Skogskultivator

Hand- screef 15.9 )

(Percentages based on 1 , 080 trees in each method. No r e a l difference between bracketed figures)

Relatively heavy but localized damage was observed to have been inflicted by the Columbia ground squirrel, seedlings being severed close to ground level. But: in general , white-tailed deer appear to be chiefly responsible for browsing damage, most of which occurs in the early spring and late fall when the forage values of the range are low.

DISCUSSION

Site PreDaration

Survival in ponderosa pine plantations depends very largely upon the amount of precipitation during the first growing season, and consequently i t may vary considerably f rom year to year (11 , 14). Korstian and Baker i 8 ) attributed nearly one third of a111 plantation losses in the Intermountain region to drought, but losses from a similar cause in British Columbia appear to exceed this estimate. During prolonged periods of low precipita- tion the demand for soil moisture is acute , and the importance of those factors which contribute to soil moisture deficiencies is accentuated. Chief among these in the Ponderosa Pine Zone are high evaporation rates and high lime content in the soil. Under these circumstances , plant competition for moisture is cr i t ical to survival, and control of the vegetation offers the forester an obvious means of improving the plant-soil moisture relationship. Indeed, Baker (1) suggested that the successful silviculture of ponderosa pine is dependent upon the control of competing vegetation, The results of the trials described above accord with this view, for the greatest improvements in survival were secured by treatments eliminating vegetation, differences being especially pronounced in the unusually dry summer of 1960. Even the provision of la teral shade, a treatment which had been shown by Maguire i 9 ) to be so beneficial to survival, was not vital when thorough ground preparation was carried out.

.

w

- 30 -

The technique used to reduce competition would not appear to be of direct importance. Chemical methods, although not tested in this W Province, may f ind valuable application in areas where soil exposure is undesirable, or where mechanized methods are precluded by the terrain (10). Physical removal of the vegetation can be accomplished in several ways : manually, by machine screefing, ploughing or cultivating. The selection of a method w i l l depend upon considerations of site, economy and convenience for, in terms of effectiveness, there is l i t t le to choose between them, provided that competition is thoroughly eliminated during the first growing season at least,

Compared with other methods, furrows may provide additional benefits , such as moisture accumulation, especially from snow melt , and reduction of evaporation by shading and sheltering the soil surface around the plant. But these were not detectable in the East Kootenay trials; they may only be apparent during periods of extreme drought as in 1960, when the superiority of ploughing over screef ing, e i ther by hand or machine, was noted in the Okanagan trials.

Future observation will show whether furrowing is to be avoided on certain si tes. This treatment results in plants being set deeper in the solum, and there is a possibility that calcium carbonate concentrations, often occurring at depths of f r o m 1 2 to 18 inches, may eventual ly res t r ic t root development, and thus affect the future growth and stability of the plantation. Early results, however, contain little evidence to warrant the anticipatiGn of such a trend.

As stated above, ideally the selection of a method is mainly based on costs, and although these are apt to vary widely, they can be minimized by using as light a machine as the site conditions w i l l permit. Under these circumstances, the expense of si te preparation wi l l be found to be almost always justified in terms of costs per surviving plant.

Site preparation is usually a prerequis i te to acceptable survival, and wider operational use of the principle is urged. The technique was not tes ted on s teep or rocky s lopes; these are general ly sub-marginal and would not repay the cost of re-afforestation. But, if necessary , t rees could probably be established by planting in manually-prepared, deep screefs. Low density planting at a ra te of 100 to 170 t r ees pe r ac re would materially reduce costs and provide adequate stocking on these sites.

W

W’

- 3 1 -

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. .

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.

Planting Stock Y

Since there is no complete1.y adequat.e system to express survival potential, planting stock in British Columbia is still described in terms of i ts age and certain easily-determined dimensions, usually root-collar diameter and length of top. A primary objective of these t r ia ls was: therefore; to determine the significance of these cr i ter ia .

F i r s t l y , the marked differences in survival; which were associated with various nursery soil amendments, confirmed the influence of nursery regime upon survival potential. It was thought that this may be due simply to the effect of the amendments upon plant size, but no clear or consistent relationship between survival and size of the several stocks was discerned. However, th.e influer-ce of mineral nutri t ion upon drought hardiness is well known 12) , and this may also account for the marked difference in survival observed between batches of plants of the same provenance and age-class but from different nurseries. Clearly, the possible influence of nursery regime upon parameters of planting stock less obvious than morphological characteristics demands acknowledge- ment in any specification of planting stock.

Secondly, the comparisons of planting stocks , segregated by nursery of origin, superficially con:firmed the conclusions of Korst ian, Wahlenberg and others who have pointed to the superiority of well balanced plants with heavy but compact , fibrous root systems. Large 2 -t 1 t rans- plants were specifically recommended for severe sites in the Intermountain Ragion ( 8 : 17) . In Eritish Columbia, the relatively small ( 1 0 per cent) but persistent difference between large and small grades of a given class of stock justifies the grading of plants within an age-class.

But survival by age-classes was only consistent in so f a r a s 2 + 1 stock gave the best survival relative to o ther c lasses of the same seedlot and nursery, Year to year variation in the quality of the classes undoubtedly has much to do with the variable relative field performance exemplified by the 1 t 2 and 2 0 East Kootenay stock, and this variability emphasizes the recognized weakness of planting stock specifications based only upon age and morpho?ogical characteristics. Until more reliable expressions of ' t rue grade' (18) or survival potential have been developed, i t seems expedient to follow those nursery procedures most consistently producing uniform, vigorous and well-balanced stock. 2 4- 1 transplants may well be the most desirable in this respect.

- 3 2 -

ACKNOWLEDGEMENTS

The Okanagan trials were facilitated by the active and financial support of S. M. Simpson Ltd. , now the S. M. Simpson Division, Crown Zellerbach (Canada) Ltd. Grateful appreciation is particularly expressed to Mr . A. Moss , lately of that company, and to Mr . D. P. Wallinger of the Reforestation Division, Brit ish Columbia Forest Service, for their encouragement and assis tance,

The writers also acknowledge their indebtedness to M r . A. R. Fraser , Research Divis ion, Bri t ish Columbia Forest Service, for his cri t icism and invaluable advice on experimental design and analyses.

- 33 -

REFERENCES W w

b 1.

2.

3.

4.

5.

6.

W

7 .

8.

9.

10.

11.

BAKER , F. S. , 1942. Reproduction of ponderosa pine at low elevations in the Sierra Nevada, Jour . For . 40(5) : p. 401-404.

BATES, C. G. and R. G. PIERCE, 1913. Forestation of the sand hills of Nebraska and Kansas. U.S. Dept. Agr i . , Fo r . Se r . Bul. 121. 49 pp.

BRITISH COLUMBIA DEPT. OF AGRIC. Climate of British Columbia. Annual Reports 1959- 1963 inclusive.

FOWELLS, H. A. : 1953. The effect of seed and stock sizes on survival and early growth of ponderosa and Jeffrey pine. Jour. For. 5117) : p. 504-507.

HALLIDAY, W. E. D. , 1937. A forest classification for Canada. Canada Dept. of Mines and Resources , For . Serv . Bul. 89, 50 pp.

KELLEY, C. C. and P. N. SPROUT, 1956. Soil survey of the Upper Kootenay and Elk River Valleys. Report No. 5, B. C. Soil Survey, B. C. Dept. of Agricul ture , Victor ia , B. C.

KELLEY, C. C. and W. D. HOLLAND: 1961. Soil survey of the Upper Columbia River Valley, Report No. 7 , B. C. Soil Survey, B. C. Dept. of Agricul ture , Victor ia , B. C.

KORSTIAN, C. F. and F. S. BAKER, 1925. Forest planting in the Intermountain region. U. S. Dept. Agric. Bul. 1264. 56 PP*

MAGUIRE, W. P. 1955. Radiation, surface temperature and seedlings surv iva l . For . Sc i l (4) : p. 277-285.

NEWTON, M. , 1963. Chemical control of competitive grass associat ions in Douglas-fir plantations. Western Weed Control Conference, Portland, Oregon. Res. Prog. Rep. p. 18-19.

PEARSON, G. A. , 1950. Management of ponderosa pine in the Southwest, U, S, Dept. A.gric. , Agric. Mon. No. 6. 218 pp.

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12.

13.

14.

15.

16.

17.

18.

19.

RUSSEL, E. W. , 1961. Soil conditions and plant growth. 9th edit. Longmans, Green & Co. Ltd. , 688 PP. Y

SHANER, B. A. , 1959. Site preparation for reforestation, using a D-7 crawler tractor with angle dozer. Jour. For . 57( 12): p. 915-916.

SHOW, S . B., 1930. Forest nursery and planting practice in the California pine region. U.S. Dept. Agric. , Circ. No. 92. 7 4 pp.

STEWART, M., 1959. Tr ia l s of planting stock, East Kootenay. B. C. For , Serv . , Fores t Research Review, p. 53-54.

STONE, E. C. , 1955. Poor survival and the physiological condition of planting stock. For. Sci. 1( 2): p. 90-94.

WAHLENBERG, W. G . , 1928. Experiments with classes of stock suitable for planting in the northern Rocky Mountains. Jour, Agric. Res. 36: p. 977-999.

WAKELY, P. C. , 1948. Physiological grades of southern pine nursery stock. Proc. SOC. Amer. For. p. 311-322.

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